Final answer:
The sudden availability of cheap mortgage loans and irresponsible lending practices led to the housing market crash and the Great Depression. The correct answer is option A. and C.
Step-by-step explanation:
The sudden availability of cheap and readily available mortgage loans, coupled with the irresponsible lending practices of banks, prompted consumers to buy larger homes and led to the housing bubble. The subsequent collapse of housing prices caused many households to owe more on their mortgages than their homes were worth, contributing to the Great Crash and The Great Depression.